The drive train for an automotive, marine or stationary industrial power system conventionally utilizes a clutch assembly interposed between an engine or driving means and a manual transmission; and a torsional vibration damper is used in the clutch assembly to neutralize any torsional vibrations or impulses emanating from the engine which would otherwise cause undesirable characteristics, e.g., impact loads, pulsation, noise, etc. in the transmission and/or driveline during operation of the system. With the use of a hydraulically-actuated torque converter, the vibration damper became unnecessary as any impulses or vibrations would be damped hydraulically in the torque converter.
In later developments where a lock-up clutch was interposed in the torque converter to by-pass the torque converter at higher speeds and provide a direct drive between the engine and transmission, the need for a vibration damper again arose. In the torque converter housing, the lock-up clutch pressure plate would be actuated by hydraulic fluid pressure from the converter to urge the plate against a friction surface in the housing to actuate the lock-up clutch. Also, the hydraulic fluid would be present in the vibration damper assembly.
Where a torque converter is not utilized and/or a torsional vibration damper is used in a dry environment, the frictional forces created in the damper due to manufacturing and loading tolerances and any frictional contact of the damper springs result in undesirable and difficult to control friction and wear characteristics. Also, centrifugal forces acting on the springs may create friction and wear patterns affecting the operation and efficiency of the damper. The present invention provides a dry environment series torsional vibration damper assembly which will overcome the problems previously discussed.